TITLE: GCN CIRCULAR NUMBER: 15111 SUBJECT: GRB 130816A: Swift/UVOT Upper Limits DATE: 13/08/19 19:49:29 GMT FROM: Stephen Holland at STScI S. T. Holland (STScI) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130816A starting 91 s after the BAT trigger (Holland et al. 2013, GCNC 15097). We do not detect any new source consistent with the REM afterglow position (Covino et al. 2013, GCNC 15098) in any of the UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the finding chart (FC) exposures and initial summed exposures are presented below. --------------------------------------------------- Filter TSTART TSTOP Exposure Mag --------------------------------------------------- white (FC) 91 241 147 >20.8 u (FC) 303 554 246 >19.9 --------------------------------------------------- v 633 1924 156 >19.2 b 559 1850 136 >20.0 u 707 1825 117 >19.5 uvw1 682 1801 117 >19.3 uvm2 658 1944 151 >19.4 uvw2 609 1900 156 >19.7 white 584 1875 284 >21.1 --------------------------------------------------- The quoted upper limits have not been corrected for the expected extinction due to the Galactic reddening along the line of sight to this burst of E(B-V) = 0.70 mag (Schlafly et al. 2011, ApJS, 737, 103). GRB 130816A was 4 degrees above the Galactic Plane, so this extinction value is highly uncertain.